Gas management and odor removal is of very significant concern in ostomy appliances. Despite the advances in various filter designs, there is still a need by ostomates for improved filter performance. Most ostomy filters currently on the market only work for a short time, in many instances less then 1 day. The key complaints have been leakage, clogging which leads to ballooning, insufficient deodorization, and reduced wear time. When some marketed filters stop working there can be leakage of stool outside of the pouch from the filter. Most of filter designs now utilize an oleophobic membrane to protect the filter from leaking in the presence of the enzymes and chemicals from feces. However, commercial ostomy pouches with or without oleophobic membranes have not addressed the clogging issue as effectively as desired by many ostomates. There are also ostomy pouches utilizing multiple membranes to improve both oleophobic and hydrophobic property in the filter, but this design increases the resistance of air flow significantly.
Most commercial ostomy filters are based on radial flow in which the gases flow along the plane of a relatively flat filter rather than directly or axially through the thickness of the filter. Such a radial or planar flow type is used in order to increase the reaction time between gases and the activated carbon. An axial flow type filter is difficult to make because of the difficulties involved in balancing the deodorization efficiency, the air flow requirement, and the profile of the filter. It is, however, desirable to have an axial flow filter that would allow a relatively small filter to be used without sacrificing the deodorization performance. A small filter size is preferred because it allows the filter to be positioned as close as possible to the seam of a pouch so that the face of the filter is not directly in front of the opening of the stoma, thus decreasing the tendency of filter clogging.
Accordingly, there is a need for an improved filtering system to improve clogging resistance. Furthermore, there is a need for an axial flow filter in order to minimize the filter profile and to make a small size filter possible.